The present invention generally relates to a pressure control system and method and, more particularly, to an improved pressure control system and method using multiple and dissimilar smart sensors to form multiple networks for a pressure control system, such as for aircraft cabins.
Many aircraft are designed to fly at relatively high altitudes, to save fuel and to avoid bad weather and turbulence at lower altitudes. As the altitude of an aircraft increases, the ambient pressure outside of the aircraft decreases and, the pressure differential between the pressure of the cabin air and the pressure of the ambient air, typically referred to as the cabin-to-ambient differential pressure, can increase as well unless otherwise controlled. With the increase of the cabin-to-ambient differential pressure beyond a certain limit, fuselage structural or seal failure may occur whereby excessive amounts of air may leak out of the aircraft cabin causing it to decompress to an undesirably low pressure. An undesirably low pressure in the aircraft cabin can cause health hazards for passengers or other undesired impacts. Thus, many aircraft are equipped with a cabin pressure control system to, among other things, maintain the cabin pressure to be within a relatively comfortable range and allow gradual changes in the cabin pressure to minimize passenger discomfort.
Modern aircraft are extremely complex systems comprising many types of electronic systems on board. These electronic systems may serve different but related functions, such as a cabin pressure control system, a flight deck display system, a crew alert system, an oxygen deploy system, and a maintenance computer system, etc. These types of systems often rely on the use of sensors to operate. For example, a cabin pressure control system for a cabin in an aircraft may use different sensors such as temperature sensors and airflow sensors to identify changes that may be needed to maintain a desired pressure in the cabin. In addition, these sensors can also be used by other systems, such as a flight deck display system, a crew alert system, and an oxygen deploy system. Packaging of the sensors in each of the cabin pressure control system, the crew alert system, or the oxygen deploy system controllers requires redundancy that is expensive and inefficient. Sharing data from all of the sensors to all of the systems using the data requires significant wiring. Wiring on the airplane to connect the various electronic systems and sensors can be expensive, heavy, hot, and difficult to install and maintain.
Traditionally, cabin pressure sensors have been located within the cabin pressure controller. Accordingly, cabin pressure sensors may be replicated in each cabin pressure controller or outflow valve controller. In some sensor architecture, command and monitor sensors may be required for each automatic control. Thus, in a two-channel system, four pressure sensors may be required for that functionality by itself, since sensors may be replicated for each channel. Thus, traditional large aircraft systems can have four to six pressure sensors performing similar functions. The duplication of sensors for each controller using the sensor can add cost and weight, and reduce the reliability of the overall system.
Furthermore, cabin pressure sensors may be connected to the cabin pressure controller in an analog or high-speed data bus to enable the timing sensitive nature of the cabin pressure controller use of the pressure signal. Specialized cabin pressure controllers may be needed to perform high speed pressure reading and oversampling techniques. In addition, cabin pressure control systems may also require time-based synchronization between the sensor and the controller. These specialized cabin pressure controllers may include high resolution analog-to-digital converters which are capable of high-accuracy pressure sensor reading and differentiating techniques. Thus, cabin pressure control functionality may not be able to be implemented on general purpose avionics computers.
In the industry and in this disclosure, a system on the aircraft may be called different names. For example, a cabin pressure control system may be called a Cabin Pressure Control System (CPCS) controller, a CPCS Main Controller, or a cabin pressure controller. All these names refer to the same system controlling the cabin pressure in an aircraft. Similarly, a flight deck display system may be simply called as a flight deck display, or a flight deck display controller, while a maintenance computer can be referred to as a maintenance computer system, or a maintenance system.
FIGS. 1(a)-1(c) depict traditional wired network systems comprising sensors, a cabin pressure controller, and other avionics components and controllers.
As shown in FIGS. 1(a)-1(c), many aircraft functions can be implemented by a general purpose computer such as Avionics A, Avionics B, or special purpose computers such as CPCS Main Controller, or other controllers such as Motor Controller A, Motor Controller B, Motor Controller C, Valve 1 Motor Controller A, Valve 1 Motor Controller B, Valve 2 Motor Controller A, or Valve 2 Motor Controller B.
As shown in FIGS. 1(a)-1(c), different sensors, such as PC Sensor A, PC Sensor B, PC Sensor C, may be used for sensing Cabin Pressures, while DP Sensor may be used for sensing the cabin-to-ambient Differential Pressure.
These sensors, such as PC Sensor A, PC Sensor B, PC Sensor C, DP Sensor may be connected by wires or conductive lines to controllers so that the sensors are physically closely coupled to the controllers to provide accurate, high resolution, pressure data or other data, in order for the cabin pressure controllers to differentiate the pressure data and obtain pressure rate data. The pressure rate computation may further require certain synchronization of the pressure sensor inputs, as the rate computation is a time-based “derivation” of the pressure.
As shown in FIGS. 1(a)-1(c), all of the system interfaces and redundancy may require significant wiring on the airplane. Each sensor is fully connected to all other component by wires. Many, if not all, of the interconnections depicted are actually twisted, shielded communication pairs. As such, there are some significant drawbacks to the current technology such as: large wiring weight; excessive wiring heat dissipation which may be caused by current through resistive conductors; large wiring space in the various routes in the airplane; low wiring reliability caused by failures of conductors, shielding, terminations, and connector pins (for the cable and the equipment side of each connection); high cost wiring maintenance for detecting wire failure; high cost of wiring bundle fabrication and installation; and limited risk failure modes—wiring must be routed redundantly and through different pathways, to prevent common mode failures due to engine rotor burst, tire burst, bird strike, etc. These drawbacks also lead to significant airplane-level design and integration problems regarding proper design of wiring bundles, accounting for wiring routes and space since wires are not easily dimensioned or modeled in a 3-D design tool. Often, wiring is one of the last systems to be integrated on the airplane, and recent Airbus A380 news show that significant delays were caused by the wiring needing to be redesigned late in the airplane program.
As can be seen, there is a need for improved apparatus and methods for pressure systems and sensors.